1. Field of the Disclosure
The present disclosure relates to a process for removing impurities from iron chloride solutions, and more particularly to a process for removing dissolved niobium, titanium, and zirconium from iron chloride solutions as filterable products.
2. Background of the Disclosure
In the chloride process for the manufacture of titanium dioxide, acidic metal chloride solutions (containing predominately iron chloride) are formed. These are generally disposed by neutralization, dewatering, and landfill, or deepwelled as hazardous waste. In some cases, the solutions are purified and sold as ferrous chloride or ferric chloride solutions, coagulants for wastewater and potable water treatment. These iron chloride solutions contain chlorides and oxychlorides of titanium, niobium, and zirconium, which slowly precipitate from solution as extremely fine solids. These fine precipitates cause difficulties in filtering the solutions because of very slow filtration rates, or cause problems in storage and handling of the solutions at the customers' sites as the fine precipitates settle and subsequently clog tanks, strainers, and pumping lines. This equipment then needs to be taken out of service for cleaning, incurring costs and interruption of service.
A need thus exists for an improved process for separating impurities such as niobium, titanium, and zirconium from these iron chloride solutions, leaving a stable iron chloride solution that does not precipitate fine solids.